Outlook.com/Hotmail intermittently blocking outgoing emails – Error 550 5.7.520 AS(4810)

Jwalin Jwalin 0 Reputation points
2026-10-15T17:01:45.52+00:00

My personal Hotmail account intermittently rejects outgoing emails with error 550 5.7.520 AS(4810), stating that the content is identified as spam.

Even a plain-text email saying "hi" to myself was rejected. Other emails work normally.

I have a Microsoft 365 subscription and have already tried basic troubleshooting without success.

Can a Microsoft moderator help escalate this to the Outlook.com team to investigate possible false-positive spam filtering?

Outlook | Web | Outlook.com | Email
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  1. AI answer

    2026-10-15T17:02:02.7633333+00:00

    A moderator escalation path is supported, but this issue can also require Microsoft Support investigation from the backend.

    For 550 5.7.520 Message blocked because it contains content identified as spam. AS(4810) on Outlook.com/Hotmail:

    1. Send a plain-text test message with no attachment, no signature, no links, and no images.
      • If that still fails, the message is likely being flagged by spam filtering rather than by a formatting or attachment issue.
    2. In Outlook on the web, review mailbox settings that could affect sending behavior:
      • Go to Settings → Mail → Junk email.
      • Review blocked senders and any unusual rules.
    3. Verify the account if prompted.
      • Microsoft can challenge sign-in activity when usage looks unusual, including travel or a new device.
      • Check the account state at https://account.microsoft.com.
    4. If the problem is intermittent and basic troubleshooting already failed, contact Microsoft Support directly from Outlook.com.
      • In Outlook.com, select the Help (?) icon and use Contact Support.
      • For this error, support may need to collect logs and investigate from the backend.
    5. If attachments are involved in the failures, test without them first.
      • Reported workarounds in similar cases include sending plain text only, converting a PDF to PNG, using a mobile device, sharing the file by OneDrive link, or zipping the attachment.
    6. If the recipient system is Microsoft and the NDR instead shows 550 5.7.511 Access denied, banned sender[...], use the delist process described in the NDR.
      • That path is specific to blocked sender/IP cases and is different from 5.7.520 content filtering.

    A Microsoft 365 subscription does not change the Outlook.com consumer support path shown above. For a personal Hotmail account, the supported escalation route is Outlook.com Help (?) → Contact Support.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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